1. Field of the Invention
Embodiments of the present invention are directed to systems and methods for the analysis and treatment of a lumen. More particularly, the present invention relates to a catheter system that is used to perform methods for the analysis and/or treatment of an occluded lumen.
2. Description of the Related Art
With the continual expansion of minimally-invasive procedures in medicine, one procedure that has been highlighted in recent years has been percutaneous transluminal angioplasty, or “PTA,” which can be used for treating diseased and partially blocked vessels such as those associated with atherosclerosis. The most prevalent use of this procedure is in the coronary arteries, the procedure more specifically called a percutaneous coronary transluminal angioplasty, or “PTCA”. These procedures utilize a flexible catheter with an inflation lumen to expand, under relatively high pressure, a balloon at the distal end of the catheter to expand a stenotic lesion.
The PTA and PTCA procedures are now commonly used in conjunction with expandable tubular structures known as stents and an angioplasty balloon is often used to expand and permanently place the stent within the lumen. An angioplasty balloon utilized with a stent is referred to as a stent delivery system. An angioplasty balloon catheter is routed into place in a target vessel through a series of interconnected vessels, generally with the aid of a guidewire and fluoroscope.
In some instances, a vessel is sufficiently blocked, e.g., with a chronic total occlusion (CTO), so that a PTA procedure is considered unsuitable because of potential complications such as a rupture of the vessel when guiding the catheter into place. Up to about 30% of coronary artery disease patients in need of treatment have CTOs. The unavailability of precise information about the complex shapes and content of CTO vessels and their lesions can make navigating a guidewire through them extremely difficult, slow, and/or risky. Other potentially less effective or more complex and costly treatments, e.g., bypass surgery, may be selected instead.
Other technologies used for traversing occluded vessels include optics-based guidance systems such as visual imaging, Optical Coherence Reflectometry (OCR), and Coherence Tomography (OCT). Since these systems typically collect coherent reflected light from the target vessel area, they can require complex, expensive optics and signal processing systems including image sensors, rotating optics, bundled optical arrays, and/or interferometers. These systems also generally do not provide much information beyond the immediate target surface. Obtaining information that goes deeper than the immediate vicinity of a catheter tip could provide useful information for navigating through blocked or partially blocked regions and reduce the risk of ruptures. Ultrasonic sensors, e.g., the IVUS device marketed by Volcano Corporation of San Diego, Calif., have also been used but will generally provide even less information than an optical system can and are generally very expensive, require a separate invasive procedure, and usually include catheter tip sizes that make them inoperable in some small coronary vessels.